The Study Of Environmental Friendly Method Of Wool Surface Modification

Wool fiber has a so-called skin-core structure. In this structure, the inner cortex is hydrophilic in nature due to the large number of polar groups contained in the polypepticie chains of the cortex. On the other hand, the outer surface of wool fibre is hydrophobic due to the presence of a high degree of disulphide cross-linkages in the cuticle layer and the fatty acids on the fiber surface, which are thought to provide a surface barrier against diffusion of dyestuffs into wool fiber. In addition, the scales on wool fiber surfaces are responsible for the directional frictional effect that is believed to be the main cause of felting shrinkage. Many chemical methods have been developed for modifying the wool fiber surface, such as chlorination and polymer deposition. In spite of the effectiveness in descaling the wool fiber, the chlorination of wool may create undesirable AOX (Absorbable Organohalogen Compounds). As a result of increasing environmental awareness and tougher government legislation on effluent discharge around the world, alternative methods with lower environment impact need to be explored and one such method is surface modification by physical means. In this paper, the effect of two physical methods, UV radiation and low temperature plasma (LTP) treatment, on wooi surface modification was investigated.The treatment of UV radiation of wool fiber was carried out in a self-made UV chamber. Wool samples were exposed to UV radiation for 40 and 60 min and the surface modification of the wool was investigated by X-ray photoelectron spectroscopy. The chemical change caused by the UV treatment was identified as surface oxidation of cystine (disulphide bonds) and thereby induced changes in the dyeing properties of the wool. The dyeability of UV-treated and untreated wool samples was determined at dyeing temperatures of 45, 50, 55 and 60℃ using CI Acid Blue 7 and UV-treated wool samples showed greater levels of dye uptake compared with those of the untreated samples. The adsorption behaviour and diffusion coefficients were also studied and the experiment results showed that dyeing properties of wool were enhanced by UV radiation due to the increased diffusion coefficient of the dyes in the treated wool fibers. The shrink-resist properties of wool fabric were not observed increased by UV radiation, however, as a pretreatment of protease degradation, the anti-pilling property of wool was evidently increased. In addition, the yellowness caused by UV radiation could be easily removed by hydrogen peroxide bleaching.In the research of wool modification by LTP treatment, the wool samples were treated by oxygen low-temperature plasma in the way of glow discharge with different treatment durations of 1, 3, 5, 10 and 15 minutes. The properties include fiber-to-fiber friction, fabric shrinkage, breaking strength, dyeability, alkali solubility, and surface chemical composition were examined quantitatively. The results of the research showed that an eroding and oxidizing effect was introduced after the plasma treatment, much oxygen was incorporated onto the fiber surface inthe form of new carboxylate functions, part of disulphide groups (S-S) in keratin were cleaved due to the oxidation of cystine residues, while the amount of aliphatic carbon on the outer layer of the cuticle was decreased, eventually induced the increased wettability and diminished barrier effect at the start of wool dyeing. As a result, diffusion of the dyestuff into the interior of the fibre is increased considerably. The antifelting effect is also achieved by plasma etching as well as by surface oxidation of the fibers. However, the shrink-resist properties obtained with plasma treatment do not impart a machine-washable finish, which is one of the most important end-user demands.Because the enzymes are natural proteins, readily biodegradable, they are favorable alternatives to many finishing chemicals. Previous work showed oxidative or reductive process was necessary prior to enzyme treatment to assist the action of the enzyme on...